Study on highly enhanced photocatalytic tetracycline degradation of type Ⅱ AgI/CuBiO and Z-scheme AgBr/CuBiO heterojunction photocatalysts.

Removal of antibiotics from aqueous solutions by photocatalysis is an advanced technology for environmental remediation. Herein, we have fabricated a series of AgX (X = I, Br)/CuBiO composites through an in-situ precipitation method. The photocatalytic activity of the obtained photocatalysts was measured by the degradation of tetracycline (TC) under visible light irradiation (λ > 420 nm). All the AgX (X = I, Br)/CuBiO composites exhibit much higher photocatalytic activity than that of pure CuBiO. The enhanced photocatalytic activity is mainly attributed to the efficient interfacial charge separation and migration in the AgX (X = I, Br)/CuBiO heterojunctions. Meanwhile, AgX (X = I, Br)/CuBiO heterojunctions display excellent photocatalytic stability, and the photocatalytic degradation rates were not obvious decreased even after five successive cycles. Based on the energy band structure, the radicals trapping and electronic spin resonance (ESR) experiments, the Z-scheme mechanism of AgBr/CuBiO and type II mechanism of AgI/CuBiO heterojunction photocatalysts were tentatively discussed, respectively.